Manage fragmentation of Data Archive files

Fragmentation can lead to degradation of read and write performance. For optimal system performance, we recommend regular detection and reduction of fragmentation. Future data archives and historic archives with auto-dynamic archiving are likely to incur fragmentation. Fragmentation is rarely an issue for fixed-size archives.

Note: Archive file types are shown in the PI SMT Archives tool, in the Type column. If the Type column is not visible, right-click the column headers and choose Type.

To control fragmentation, perform online reprocessing of only those archives that are highly fragmented. Online reprocessing allocates new, contiguous sectors for the archive files you reprocess. This method enables you to keep data online, and therefore available, as much as possible.

1. Defragment the drive; run both the analysis and the defragmentation processes.

   Note: The archive files that are registered with the Data Archive server are analyzed but not defragmented, because they are locked.

2. Use the fragmentation report to identify archive files that are highly fragmented.

3. Reprocess those archive files, online.

   For more information, see Archive reprocessing.

To perform a complete defragmentation of a full Data Archive system, the Data Archive server must be stopped. While it is stopped, you can defragment all files. It might be convenient to do this when you have scheduled system downtime for maintenance.

For more complicated scenarios, contact AVEVA Technical Support. See the Customer Portal.